Retina

Bulka CM, Dammann O, Santos HP, VanderVeen DK, Smeester L, Fichorova R, O'Shea MT, Fry RC. Placental CpG Methylation of Inflammation, Angiogenic, and Neurotrophic Genes and Retinopathy of Prematurity. Invest Ophthalmol Vis Sci 2019;60(8):2888-2894.Abstract
Purpose: Extremely preterm infants are at increased risk for retinopathy of prematurity (ROP). We previously identified several inflammatory proteins that were expressed early in life and are associated with an increased risk of ROP and several angiogenic and neurotrophic growth factors in the neonatal systemic circulation that are associated with a lower risk of ROP. In this paper, we report the results of a set of analyses designed to test the hypothesis that placental CpG methylation levels of 12 inflammation-, angiogenic-, and neurotrophic-associated genes predict the occurrence of prethreshold ROP in extremely preterm newborns. Methods: We used placental CpG methylation data from 395 newborns from the Extremely Low Gestational Age Newborns study. Results: Multivariable regression models revealed that placental DNA methylation of 16 CpG sites representing 8 genes were associated with prethreshold ROP. Specifically, CpG methylation in the serum amyloid A SAA1 and SAA2, brain-derived neurotrophic factor (BDNF), myeloperoxidase (MPO), C-reactive protein (CRP), angiopoietin 1 (ANGPT1), and tumor necrosis factor receptor superfamily member 1B (TNFRSF1B) genes was associated with a lower risk of prethreshold ROP. Conversely, CpG methylation at three probes within tumor necrosis factor receptor superfamily member 1A (TNFRSF1A) and in two alternative probes within the BDNF and ANGPT1 genes was associated with an increased risk of ROP. Conclusions: CpG methylation may be a useful marker for improving ROP prediction, opening the opportunity for early intervention to lessen disease severity.
Wang J, Xu D, Zhu T, Zhou Y, Chen X, Wang F, Zhang J, Tian H, Gao F, Zhang J, Jin C, Xu J, Lu L, Liu Q, Xu G-T. Identification of two novel RHO mutations in Chinese retinitis pigmentosa patients. Exp Eye Res 2019;188:107726.Abstract
Retinitis pigmentosa (RP) is a group of genetically heterogeneous retinal diseases with more than 80 identified causative genes to date. Mutations in the RHO (rhodopsin, OMIM, 180380) are the most common cause of autosomal dominant RP (adRP) worldwide. RHO is also one of the few RP genes that can cause autosomal recessive RP (arRP). To explore the frequency of RP mutations in Chinese populations, panel-based NGS (next-generation sequencing) screening and Sanger sequencing validation were performed for RP patients from 72 unrelated Chinese families. Here we reported the identified mutations only in the RHO gene. Our results showed that 4 mutations in RHO were detected in 5 (6.94%) of the 72 RP families, including two known missense mutations, c.158C > G (p.P53R) and c.551A > C (p.Q184P), and two novel mutations, c.34delC (p.P12NA) and c.82C > T (p.Q28X). The c.34delC (p.P12NA) mutation was detected in heterozygous state in one patient with intermediate RP phenotype. The c.82C > T (p.Q28X) mutation was found in a homozygous state in one proband with advanced RP phenotype at the age of 32. Clinical examination of the heterozygous carriers of c.82C > T (p.Q28X) in that family showed that the father at the age of 60s experienced no symptoms of RP and normal fundus examinations but displayed reduced electroretinography (ERG) and abnormal visual field. The sister and brother at the age of 30s showed no typical aspects of RP phenotypes. Our results not only expand the mutation spectrum of the RHO gene, but also suggest that the 2 null mutations might play minor dominant effects, leading to less severe and slower retinal degeneration in heterozygous state and more severe phenotype in homozygous state.
Ung C, Miller JB. Intraoperative Optical Coherence Tomography in Vitreoretinal Surgery. Semin Ophthalmol 2019;:1-6.Abstract
Intraoperative OCT (OCT) is an emerging modality capable of displaying real-time OCT images to the surgeon during surgery. The use of iOCT during vitreoretinal surgery improves our understanding of the tissue alterations that occur during surgical manipulations, which may impact surgical decision-making. We review the current OCT modalities and clinical applications of OCT.
Perepelkina T, Kegeles E, Baranov PY. Optimized conditions and use of synthetic matrix for retinal differentiation from pluripotent cells. Tissue Eng Part C Methods 2019;Abstract
PURPOSE: Since it was first introduced in 2011, three-dimensional "Sasai" method for retinal differentiation became a strategy of choice for retinal tissue and neuron production. It is based on the recapitulation of retinal development and requires several stages: aggregate formation, neuroectoderm induction, and eye field induction, followed by retinal maturation. In order to achieve the consistency of retinal differentiation needed for drug discovery and cell transplantation we have attempted to improve spheroid formation as well as approach xeno-free conditions. METHODS: In this study we compared the effect of cell culture plate shape and material, medium viscosity, lipid and bovine serum albumin concentrations on aggregate formation from mouse embryonic stem cells. We have also assessed the possibility of substituting Matrigel with the synthetic vitronectin-mimicking oligopeptide. RX-GFP mES cell line used for experiments. The dose-response of synthetic ECM has been assessed and quantified by live fluorescence microscopy, immunohistochemistry, flow cytometry and qPCR for early retinal development genes (Rx, Pax6, Lhx2, Sox2, Six6). RESULTS: The comparison of seeding conditions at 24hr. post seeding showed the dose-dependent effects of lipids (lipids concentration of 2% resulted in 100% efficiency of aggregate formation and significant increase in size to 532.8 ± 31.87um, p< 0.05); and viscosity (methylcellulose concentration of 0.06% in OV medium showed 100% efficiency and increase in aggregate size 532±19.23 um, p<0.01). The addition of synthetic matrix resulted in retinal differentiation (34.47% of RX as detected by flow cytometry compared to 33.8%, observed with Matrigel). The early retinal genes expression at day 7 was confirmed by qPCR. CONCLUSIONS: We present the optimized conditions for 3D retinal differentiation including the option of xeno-free extracellular matrix. These defined medium conditions significantly decrease the variability within and between batches and allow substantial scale up of retinal tissue and cell production for drug discovery, disease modeling and transplantation purposes.
Bagdonaite-Bejarano L, Hansen RM, Fulton AB. Microperimetry in Three Inherited Retinal Disorders. Semin Ophthalmol 2019;:1-6.Abstract
Microperimetry (MP) is used to assess visual sensitivity mediated by the central retina. As such, MP performance is a candidate outcome measure for gene therapy trials. Herein, we review MP results in three inherited retinal disorders for which gene therapy trials have been initiated-choroideremia, Stargardt disease, and X-linked juvenile retinoschisis. Each of these disorders typically presents in childhood and each has distinct effects on the central retina. Our review indicates that microperimetry is feasible in each of these conditions. The MP sensitivity maps vary among conditions consistent with known effects of each of the three conditions. There is, however, within each of the three disorders considerable variability in fixation stability and in the pattern of sensitivity loss. Microperimetry is a valuable tool for monitoring functional aspects of central retina in an individual patient, especially in combination with other modalities such as OCT, autofluorescence, and acuity and thus may contribute to evaluating the efficacy of gene treatments. Variability of the MP parameters raises some cautions in application of MP as an outcome measure in treatment trials that may have small sample sizes. Nonetheless, we suspect that MP will continue to have a rightful place in future gene therapy trials.
Berner D, Hoja U, Zenkel M, Ross JJ, Uebe S, Paoli D, Frezzotti P, Rautenbach RM, Ziskind A, Williams SE, Carmichael TR, Ramsay M, Topouzis F, Chatzikyriakidou A, Lambropoulos A, Sundaresan P, Ayub H, Akhtar F, Qamar R, Zenteno JC, Cruz-Aguilar M, Astakhov YS, Dubina M, Wiggs J, Ozaki M, Kruse FE, Aung T, Reis A, Khor CC, Pasutto F, Schlötzer-Schrehardt U. The protective variant rs7173049 at LOXL1 locus impacts on retinoic acid signaling pathway in pseudoexfoliation syndrome. Hum Mol Genet 2019;Abstract
LOXL1 (lysyl oxidase-like 1) has been identified as the major effect locus in pseudoexfoliation (PEX) syndrome, a fibrotic disorder of the extracellular matrix and frequent cause of chronic open-angle glaucoma. However, all known PEX-associated common variants show allele effect reversal in populations of different ancestry, casting doubt on their biological significance. Based on extensive LOXL1 deep sequencing, we report here the identification of a common noncoding sequence variant, rs7173049A>G, located downstream of LOXL1, consistently associated with a decrease in PEX risk (OR=0.63, p=6.33x10-31) in nine different ethnic populations. We provide experimental evidence for a functional enhancer-like regulatory activity of the genomic region surrounding rs7173049 influencing expression levels of ISLR2 (immunoglobulin superfamily containing leucine-rich repeat protein 2) and STRA6 (stimulated by retinoic acid receptor 6), apparently mediated by allele-specific binding of the transcription factor THRβ (thyroid hormone receptor beta). We further show that the protective rs7173049-G allele correlates with increased tissue expression levels of ISLR2 and STRA6 and that both genes are significantly downregulated in tissues of PEX patients together with other key components of the STRA6 receptor-driven retinoic acid signaling pathway. siRNA-mediated downregulation of retinoic acid signaling induces upregulation of LOXL1 and PEX-associated matrix genes in PEX-relevant cell types. These data indicate that dysregulation of STRA6 and impaired retinoid metabolismare involved in the pathophysiology of PEX syndrome and that the variant rs7173049-G, which represents the first common variant at the broad LOXL1 locus without allele effect reversal, mediates a protective effect through upregulation of STRA6 in ocular tissues.
Wang SK, Xue Y, Rana P, Hong CM, Cepko CL. Soluble CX3CL1 gene therapy improves cone survival and function in mouse models of retinitis pigmentosa. Proc Natl Acad Sci U S A 2019;116(20):10140-10149.Abstract
Retinitis pigmentosa (RP) is a disease that initially presents as night blindness due to genetic deficits in the rod photoreceptors of the retina. Rods then die, causing dysfunction and death of cone photoreceptors, the cell type that mediates high acuity and color vision, ultimately leading to blindness. We investigated immune responses in mouse models of RP and found evidence of microglia activation throughout the period of cone degeneration. Using adeno-associated vectors (AAVs), delivery of genes encoding microglial regulatory signals led to the identification of AAV serotype 8 (AAV8) soluble CX3CL1 (sCX3CL1) as a promising therapy for degenerating cones. Subretinal injection of AAV8-sCX3CL1 significantly prolonged cone survival in three strains of RP mice. Rescue of cones was accompanied by improvements in visual function. AAV8-sCX3CL1 did not affect rod survival, microglia localization, or inflammatory cytokine levels in the retina. Furthermore, although RNA sequencing of microglia demonstrated marked transcriptional changes with AAV8-sCX3CL1, pharmacological depletion of up to ∼99% of microglia failed to abrogate the effect of AAV8-sCX3CL1 on cone survival. These findings indicate that AAV8-sCX3CL1 can rescue cones in multiple mouse models of RP via a pathway that does not require normal numbers of microglia. Gene therapy with sCX3CL1 is a promising mutation-independent approach to preserve vision in RP and potentially other forms of retinal degeneration.
Tsoka P, Barbisan PR, Kataoka K, Chen XN, Tian B, Bouzika P, Miller JW, Paschalis EI, Vavvas DG. NLRP3 inflammasome in NMDA-induced retinal excitotoxicity. Exp Eye Res 2019;181:136-144.Abstract
N-methyl-D-aspartate (NMDA)-induced excitotoxicity is an acute form of experimental retinal injury as a result of overactivation of glutamate receptors. NLRP3 (nucleotide-binding domain, leucine-rich-repeat containing family, pyrin domain containing-3) inflammasome, one of the most studied sensors of innate immunity, has been reported to play a critical role in retinal neurodegeneration with controversial implications regarding neuroprotection and cell death. Thus far, it has not been elucidated whether NMDA-mediated excitotoxicity can trigger NLRP3 inflammasome in vivo. Moreover, it is unknown if NLRP3 is beneficial or detrimental to NMDA-mediated retinal cell death. Here, we employed a murine model of NMDA-induced retinal excitotoxicity by administering 100 nmoles of NMDA intravitreally, which resulted in massive TUNEL (TdT-dUTP terminal nick-end labelling) cell death in all retinal layers and especially in retinal ganglion cells (RGCs) 24 h post injection. NMDA insult in the retina potentiates macrophage/microglia cell infiltration, primes the NLRP3 inflammasome in a transcription-dependent manner and induces the expression of interleukin-1β (IL-1β). However, despite NLRP3 inflammasome upregulation, systemic deletion of Nlrp3 or Casp1 (caspase-1) did not significantly alter the NMDA-induced, excitotoxicity-mediated TUNEL retinal cell death at 24 h (acute phase). Similarly, the deletion of the two aforementioned genes did not alter the survival of the Brn3a (brain-specific homeobox/POU domain protein 3A) RGCs in a significant way at 3- or 7-days post injection (long-term phase). Our results indicate that NMDA-mediated retinal excitotoxicity induces immune cell recruitment and NLRP3 inflammasome activity even though inflammasome-mediated neuroinflammation is not a leading contributing factor to cell death in this type of retinal injury.
Al-Moujahed A, Tian B, Efstathiou NE, Konstantinou EK, Hoang M, Lin H, Miller JW, Vavvas DG. Receptor interacting protein kinase 3 (RIP3) regulates iPSCs generation through modulating cell cycle progression genes. Stem Cell Res 2019;35:101387.Abstract
The molecular mechanisms involved in induced pluripotent stem cells (iPSCs) generation are poorly understood. The cell death machinery of apoptosis-inducing caspases have been shown to facilitate the process of iPSCs reprogramming. However, the effect of other cell death processes, such as programmed necrosis (necroptosis), on iPSCs induction has not been studied. In this study, we investigated the role of receptor-interacting protein kinase 3 (RIP3), an essential regulator of necroptosis, in reprogramming mouse embryonic fibroblast cells (MEFs) into iPSCs. RIP3 was found to be upregulated in iPSCs compared to MEFs. Deletion of RIP3 dramatically suppressed the reprogramming of iPSCs (~82%). RNA-seq analysis and qRT-PCR showed that RIP3 KO MEFs expressed lower levels of genes that control cell cycle progression and cell division and higher levels of extracellular matrix-regulating genes. The growth rate of RIP3 KO MEFs was significantly slower than WT MEFs. These findings can partially explain the inhibitory effects of RIP3 deletion on iPSCs generation and show for the first time that the necroptosis kinase RIP3 plays an important role in iPSC reprogramming. In contrast to RIP3, the kinase and scaffolding functions of RIPK1 appeared to have distinct effects on reprogramming.
Chung DC, Bertelsen M, Lorenz B, Pennesi ME, Leroy BP, Hamel CP, Pierce E, Sallum J, Larsen M, Stieger K, Preising M, Weleber R, Yang P, Place E, Liu E, Schaefer G, DiStefano-Pappas J, Elci OU, McCague S, Wellman JA, High KA, Reape KZ. The Natural History of Inherited Retinal Dystrophy Due to Biallelic Mutations in the RPE65 Gene. Am J Ophthalmol 2019;199:58-70.Abstract
PURPOSE: To delineate the natural history of visual parameters over time in individuals with biallelic RPE65 mutation-associated inherited retinal dystrophy (IRD); describe the range of causative mutations; determine potential genotype/phenotype relationships; and describe the variety of clinical diagnoses. DESIGN: Global, multicenter, retrospective chart review. METHODS: Study Population: Seventy individuals with biallelic RPE65 mutation-associated IRD. PROCEDURES: Data were extracted from patient charts. MEASUREMENTS: Visual acuity (VA), Goldmann visual field (GVF), optical coherence tomography, color vision testing, light sensitivity testing, and electroretinograms (retinal imaging and fundus photography were collected and analyzed when available). RESULTS: VA decreased with age in a nonlinear, positive-acceleration relationship (P < .001). GVF decreased with age (P < .0001 for both V4e and III4e), with faster GVF decrease for III4e stimulus vs V4e (P = .0114, left eye; P = .0076, right eye). On average, a 1-year increase in age decreased III4e GVF by ∼25 sum total degrees in each eye while V4e GVF decreased by ∼37 sum total degrees in each eye, although individual variability was observed. A total of 78 clinical diagnoses and 56 unique RPE65 mutations were recorded, without discernible RPE65 mutation genotype/phenotype relationships. CONCLUSIONS: The number of clinical diagnoses and lack of a consistent RPE65 mutation-to-phenotype correlation underscore the need for genetic testing. Significant relationships between age and worsening VA and GVF highlight the progressive loss of functional retina over time. These data may have implications for optimal timing of treatment for IRD attributable to biallelic RPE65 mutations.
Jiao C, Eliott D, Spee C, He S, Wang K, Mullins RF, Hinton DR, Sohn EH. APOPTOSIS AND ANGIOFIBROSIS IN DIABETIC TRACTIONAL MEMBRANES AFTER VASCULAR ENDOTHELIAL GROWTH FACTOR INHIBITION: Results of a Prospective Trial. Report No. 2. Retina 2019;39(2):265-273.Abstract
PURPOSE: We sought to characterize the angiofibrotic and apoptotic effects of vascular endothelial growth factor (VEGF)-inhibition on fibrovascular epiretinal membranes in eyes with traction retinal detachment because of proliferative diabetic retinopathy. METHODS: Membranes were excised from 20 eyes of 19 patients (10 randomized to intravitreal bevacizumab, 10 controls) at vitrectomy. Membranes were stained with antibodies targeting connective tissue growth factor (CTGF) or VEGF and colabeled with antibodies directed against endothelial cells (CD31), myofibroblasts, or retinal pigment epithelium markers. Quantitative and colocalization analyses of antibody labeling were obtained through immunofluorescence confocal microscopy. Masson trichrome staining, cell counting of hematoxylin and eosin sections, and terminal dUTP nick-end labeling staining were performed. RESULTS: High levels of fibrosis were observed in both groups. Cell apoptosis was higher (P = 0.05) in bevacizumab-treated membranes compared with controls. The bevacizumab group had a nonsignificant reduction in colocalization in CD31-CTGF and cytokeratin-VEGF studies compared with controls. Vascular endothelial growth factor in extracted membranes was positively correlated with vitreous levels of VEGF; CTGF in extracted membranes was negatively correlated with vitreous levels of CTGF. CONCLUSION: Bevacizumab suppresses vitreous VEGF levels, but does not significantly alter VEGF or CTGF in diabetic membranes that may be explained by high baseline levels of fibrosis. Bevacizumab may cause apoptosis within fibrovascular membranes.
Peng Y-R, Shekhar K, Yan W, Herrmann D, Sappington A, Bryman GS, van Zyl T, Do MTH, Regev A, Sanes JR. Molecular Classification and Comparative Taxonomics of Foveal and Peripheral Cells in Primate Retina. Cell 2019;176(5):1222-1237.e22.Abstract
High-acuity vision in primates, including humans, is mediated by a small central retinal region called the fovea. As more accessible organisms lack a fovea, its specialized function and its dysfunction in ocular diseases remain poorly understood. We used 165,000 single-cell RNA-seq profiles to generate comprehensive cellular taxonomies of macaque fovea and peripheral retina. More than 80% of >60 cell types match between the two regions but exhibit substantial differences in proportions and gene expression, some of which we relate to functional differences. Comparison of macaque retinal types with those of mice reveals that interneuron types are tightly conserved. In contrast, projection neuron types and programs diverge, despite exhibiting conserved transcription factor codes. Key macaque types are conserved in humans, allowing mapping of cell-type and region-specific expression of >190 genes associated with 7 human retinal diseases. Our work provides a framework for comparative single-cell analysis across tissue regions and species.
Makino CL, Duda T, Pertzev A, Isayama T, Geva P, Sandberg MA, Sharma RK. Modes of Accessing Bicarbonate for the Regulation of Membrane Guanylate Cyclase (ROS-GC) in Retinal Rods and Cones. eNeuro 2019;6(1)Abstract
The membrane guanylate cyclase, ROS-GC, that synthesizes cyclic GMP for use as a second messenger for visual transduction in retinal rods and cones, is stimulated by bicarbonate. Bicarbonate acts directly on ROS-GC1, because it enhanced the enzymatic activity of a purified, recombinant fragment of bovine ROS-GC1 consisting solely of the core catalytic domain. Moreover, recombinant ROS-GC1 proved to be a true sensor of bicarbonate, rather than a sensor for CO. Access to bicarbonate differed in rods and cones of larval salamander, , of unknown sex. In rods, bicarbonate entered at the synapse and diffused to the outer segment, where it was removed by Cl-dependent exchange. In contrast, cones generated bicarbonate internally from endogenous CO or from exogenous CO that was present in extracellular solutions of bicarbonate. Bicarbonate production from both sources of CO was blocked by the carbonic anhydrase inhibitor, acetazolamide. Carbonic anhydrase II expression was verified immunohistochemically in cones but not in rods. In addition, cones acquired bicarbonate at their outer segments as well as at their inner segments. The multiple pathways for access in cones may support greater uptake of bicarbonate than in rods and buffer changes in its intracellular concentration.
Chen T-C, She P-Y, Chen DF, Lu J-H, Yang C-H, Huang D-S, Chen P-Y, Lu C-Y, Cho K-S, Chen H-F, Su W-F. Polybenzyl Glutamate Biocompatible Scaffold Promotes the Efficiency of Retinal Differentiation toward Retinal Ganglion Cell Lineage from Human-Induced Pluripotent Stem Cells. Int J Mol Sci 2019;20(1)Abstract
Optic neuropathy is one of the leading causes of irreversible blindness caused by retinal ganglion cell (RGC) degeneration. The development of induced pluripotent stem cell (iPSC)-based therapy opens a therapeutic window for RGC degeneration, and tissue engineering may further promote the efficiency of differentiation process of iPSCs. The present study was designed to evaluate the effects of a novel biomimetic polybenzyl glutamate (PBG) scaffold on culturing iPSC-derived RGC progenitors. The iPSC-derived neural spheres cultured on PBG scaffold increased the differentiated retinal neurons and promoted the neurite outgrowth in the RGC progenitor layer. Additionally, iPSCs cultured on PBG scaffold formed the organoid-like structures compared to that of iPSCs cultured on cover glass within the same culture period. With RNA-seq, we found that cells of the PBG group were differentiated toward retinal lineage and may be related to the glutamate signaling pathway. Further ontological analysis and the gene network analysis showed that the differentially expressed genes between cells of the PBG group and the control group were mainly associated with neuronal differentiation, neuronal maturation, and more specifically, retinal differentiation and maturation. The novel electrospinning PBG scaffold is beneficial for culturing iPSC-derived RGC progenitors as well as retinal organoids. Cells cultured on PBG scaffold differentiate effectively and shorten the process of RGC differentiation compared to that of cells cultured on coverslip. The new culture system may be helpful in future disease modeling, pharmacological screening, autologous transplantation, as well as narrowing the gap to clinical application.
Paschalis EI, Lei F, Zhou C, Chen XN, Kapoulea V, Hui P-C, Dana R, Chodosh J, Vavvas DG, Dohlman CH. Microglia Regulate Neuroglia Remodeling in Various Ocular and Retinal Injuries. J Immunol 2019;202(2):539-549.Abstract
Reactive microglia and infiltrating peripheral monocytes have been implicated in many neurodegenerative diseases of the retina and CNS. However, their specific contribution in retinal degeneration remains unclear. We recently showed that peripheral monocytes that infiltrate the retina after ocular injury in mice become permanently engrafted into the tissue, establishing a proinflammatory phenotype that promotes neurodegeneration. In this study, we show that microglia regulate the process of neuroglia remodeling during ocular injury, and their depletion results in marked upregulation of inflammatory markers, such as , , and in the retina, and abnormal engraftment of peripheral CCR2 CX3CR1 monocytes into the retina, which is associated with increased retinal ganglion cell loss, retinal nerve fiber layer thinning, and pigmentation onto the retinal surface. Furthermore, we show that other types of ocular injuries, such as penetrating corneal trauma and ocular hypertension also cause similar changes. However, optic nerve crush injury-mediated retinal ganglion cell loss evokes neither peripheral monocyte response in the retina nor pigmentation, although peripheral CX3CR1 and CCR2 monocytes infiltrate the optic nerve injury site and remain present for months. Our study suggests that microglia are key regulators of peripheral monocyte infiltration and retinal pigment epithelium migration, and their depletion results in abnormal neuroglia remodeling that exacerbates neuroretinal tissue damage. This mechanism of retinal damage through neuroglia remodeling may be clinically important for the treatment of patients with ocular injuries, including surgical traumas.

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